The present invention relates to visualization of medical devices within the human body generally and more particularly to visualization of implantable cardiac pacing and defibrillation leads by means of ultrasound.
Cardiac pacing and defibrillation leads are generally put in under fluoroscopic observation, allowing the physician to follow the course of the lead as it is passed through the venous system into the heart. However, as fluoroscopes are extremely expensive, a less costly method of visualization of cardiac pacing and defibrillation leads would be desirable. One alternative mechanism for visualization of devices placed within the body is by means of ultrasound. In U.S. Pat. No. 5,421,336 issued to DeBernardis, incorporated herein by reference in its entirety, the use of a vibrator coupled to an interventional device to enhance its visibility in an ultrasound scan is disclosed. In particular, the vibrator member induces three-dimensional flexural waves which propagate along the member, causing it to light up on the display of the ultrasound scan. The DeBernardis patent also discloses attaching a vibrator to a member such as a guidewire or stylet inserted into a tubular probe, to localize the probe. A second method of visualizing a catheter or pacing lead is to place an ultrasound sensor on or in the lead body and employ the sensor in conjunction with an ultrasound imaging system to localize the sensor in the ultrasound scan. Examples of such localization systems are disclosed in U.S. Pat. No. 5,161,536 issued to Vilkomerson et al and in U.S. Pat. No. 4,697,595 issued to Breyer et al., both incorporated herein by reference in their entireties.